Risk Factor For Thyroid Cancer Research Articles

Are pregnancy, parity, menstruation and breastfeeding risk factors for thyroid cancer? Results from the Korea National Health and Nutrition Examination Survey, 2010-2015.

It is unclear whether reproductive factors such as pregnancy, parity, menstruation, and breastfeeding are risk factors for thyroid cancer. The aim of this study was to evaluate the association of reproductive factors with thyroid cancer risk. Large-scale nation-wide cross-sectional data were analysed from representative samples from the Korea National Health and Nutrition Examination Survey V-VI (2010-2015). In this study, 38086 people over the age of 18years were enrolled, of which 241 had a diagnosis of thyroid cancer. Of 21543 female subjects, 210 had thyroid cancer. In logistic regression analysis, pregnancy, parity and number of reproductive years (period between menarche and menopause, excluding breastfeeding period) were significantly associated with thyroid cancer after adjusting for age, body mass index and smoking. However, the number of pregnancies did not show a linear relationship with thyroid cancer. Among breastfeeding women, total duration of breastfeeding and number of babies breastfed significantly decreased the risk for thyroid cancer. Our findings suggest that reproductive factors can be associated with the development of thyroid cancer. A large prospective cohort study is needed to clarify the causality.

Vitamin D deficiency as a risk factor for thyroid cancer: A meta-analysis of case-control studies.

The association between vitamin D deficiency and thyroid cancer is controversial. Some studies have demonstrated that higher serum vitamin D levels might protect against thyroid cancer, whereas others have not, or have even indicated the opposite to be the case. The aim of this meta-analysis was to investigate the association between vitamin D deficicency and thyroid cancer and propose that vitamin D deficiency is a risk factor for thyroid cancer. This was a meta-analysis of 14 articles of the association between vitamin D deficiency and thyroid cancer. Databases including PubMed, Cochrane library, Sinomed, CNKI, Wanfang, and clinical trial register centers, were searched for case-control studies of vitamin D in thyroid cancer. Fourteen studies were included in this meta-analysis. A fixed-effect model was used to merge the standardized mean difference value of serum 25-hydroxyvitamin D levels. The pooled effect showed that the levels of serum 25-hydroxyvitamin D were lower in patients with thyroid cancer preoperatively than in the controls (-0.22; 95% confidence interval [CI], -0.36 to -0.09; P = 0.001). There was no difference after thyroid cancer patients underwent thyroidectomy (-0.19; 95% CI, -0.47 to 0.10; P = 0.21). A fixed-effect model was used to pool the odds ratio of thyroid cancer and vitamin D deficiency. It showed that the pooled odds ratio from six studies was 1.30 (95% CI, 1.00-1.69; P = 0.05). Subgroup analysis of 25-hydroxyvitamin D levels between different pathologic characteristics in patients with thyroid cancer was summarized, but no statistical differences were determined. Lower serum 25-hydroxyvitamin D levels were associated with increased risk for thyroid cancer. On the other hand, vitamin D deficiency may act as a risk factor for thyroid cancer.

Association of Obesity and Thyroid Cancer at a Tertiary Care Hospital in Pakistan.

ObjectiveThyroid cancer (TC) is one of the most common endocrine malignancies with a rapidly increasing worldwide presence. In Pakistan, it is more prevalent in females than males and has an incidence rate of 2.1%. Obesity and excess body mass index (BMI) has been linked to several cancers and is thought to be a risk factor for TC. We aim to investigate the incidence of TC in our population and understand it’s correlation with obesity.SubjectsThe study was a retrospective case series conducted in the years 2000 to 2014, at the Aga Khan University Hospital (AKUH), Karachi, Pakistan where 156 patients who had been diagnosed and treated for TC were analyzed. Clinicopathological data was collected from medical records of these patients and weight and height were measured, pre-surgery, post-surgery, and at follow up. The BMI was correlated with patient variables for any significant associations.ResultsThe patient set comprised of 38.5% males and 61.5% females with a mean age of 47.77 (SD ± 14.35). The BMI was significantly associated with age as 72.8% of participants were obese and >45 years old as compared to 27.2% who were under 45 years and obese (p-value <0.001). Upon comparison of the pre-surgery, post-surgery, and current mean BMI, Bonferroni pairwise comparisons showed no significant difference (p>0.999).Conclusion The majority of-of TC patients among the Pakistani population were obese and female. Age was significantly associated with the risk of having a higher BMI. Moreover, differences in BMI pre and post-surgery could not be statistically proven.

The spatio-temporal distribution and risk factors of thyroid cancer during rapid urbanization–A case study in China

BackgroundIncidences of thyroid cancer (TC) have been increasing worldwide in recent decades. In this research, we aimed to analyze the spatiotemporal pattern of TC and explore relevant environmental risk factors in Hangzhou (HZ), which is rapidly urbanizing and home to the highest TC incidence in China. MethodsSpatial scan statistic was employed to analyze the spatiotemporal pattern of TC in HZ from 2008 to 2012. The geographically weighted regression model (GWR) was implemented to explore environmental risk factors. Its performance was compared to the traditional ordinary least squares model (OLS). ResultsA total of 7147 TC cases (5385 female and 1762 male) were diagnosed in HZ from 2008 to 2012. High TC clusters were detected in the northeast, urban areas and expanded outwards while low clusters were located in the southwest rural areas. The GWR model generally performed better than the OLS in analyzing the associations between TC incidence and environmental factors. The industrial density, chemical oxygen demand of wastewater (COD) and the percentage of building area had a strong positive influence on the TC in the northeastern suburb areas of HZ, while the elevation, slope and the percentage of forest area had a significant negative correlation with TC in the middle, rural areas of HZ. Meanwhile, the accessibility to health care might have an impact on the TC incidence. ConclusionHigh clusters were mostly located in the northeastern urban areas and showed an expansion process from the center urban area to the suburb area, especially for female TC. Intensive industrial activities and the emission of organic pollutants, which positively correlated with the high TC clusters in the northeast suburb areas of HZ, should get proper attention.

Germline Variants in DNA Repair Genes, Diagnostic Radiation, and Risk of Thyroid Cancer.

Background: Radiation exposure is a well-documented risk factor for thyroid cancer; diagnostic imaging represents an increasing source of exposure. Germline variations in DNA repair genes could increase risk of developing thyroid cancer following diagnostic radiation exposure. No studies have directly tested for interaction between germline mutations and radiation exposure.Methods: Using data and DNA samples from a Connecticut population-based case-control study performed in 2010 to 2011, we genotyped 440 cases of incident thyroid cancer and 465 population-based controls for 296 SNPs in 52 DNA repair genes. We used multivariate unconditional logistic regression models to estimate associations between each SNP and thyroid cancer risk, as well as to directly estimate the genotype-environment interaction between each SNP and ionizing radiation.Results: Three SNPs were associated with increased risk of thyroid cancer and with thyroid microcarcinoma: HUS rs2708896, HUS rs10951937, and MGMT rs12769288. No SNPs were associated with increased risk of larger tumor (>10 mm) in the additive model. The gene-environment interaction analysis yielded 24 SNPs with Pinteraction < 0.05 for all thyroid cancer, 12 SNPs with Pinteraction < 0.05 for thyroid microcarcinoma, and 5 SNPs with Pinteraction < 0.05 for larger tumors.Conclusions: Germline variants in DNA repair genes are associated with thyroid cancer risk and are differentially associated with thyroid microcarcinoma and large tumor size. Our study provides the first evidence that germline genetic variations modify the association between diagnostic radiation and thyroid cancer risk.Impact: Thyroid microcarcinoma may represent a distinct subset of thyroid cancer. The effect of diagnostic radiation on thyroid cancer risk varies by germline polymorphism. Cancer Epidemiol Biomarkers Prev; 27(3); 285-94. ©2017 AACR.

Occupational radiation exposure and thyroid cancer incidence in a cohort of U.S. radiologic technologists, 1983-2013.

Although childhood exposure to ionizing radiation is a well-established risk factor for thyroid cancer, the risk associated with adulthood exposure remains unclear. We prospectively examined the association between cumulative, low-to-moderate dose occupational radiation exposure to the thyroid and thyroid cancer incidence in the U.S. Radiologic Technologists cohort. The study included 89,897 members who completed at least two of four mailed questionnaires and were cancer-free at the time of the first questionnaire. Cumulative occupational thyroid radiation dose (mean = 57 mGy, range = 0-1,600 mGy) was estimated based on self-reported work histories, historical data and, during the years 1960-1997, 783,000 individual film badge measurements. During follow-up, we identified 476 thyroid cancer cases. We used Poisson regression to estimate excess relative risk of thyroid cancer per 100 milliGray (ERR/100 mGy) absorbed dose to the thyroid gland. After adjusting for attained age, sex, birth year, body mass index and pack-years smoked, we found no association between thyroid dose and thyroid cancer risk (ERR/100 mGy = -0.05, 95% CI <-0.10, 0.34). In this large cohort study of radiologic technologists, protracted, low-to-moderate dose ionizing radiation exposure to the thyroid gland in adulthood was not associated with an increased risk of thyroid cancer.

Risk factors for well-differentiated thyroid cancer in men.

Thyroid cancers are relatively rare tumors that appear more frequently in women than in men. Accordingly, most studies focus on studying risk factors for thyroid cancer in women and consequently on various hormonal or reproductive factors that are specific for women. The aim of our study was to examine risk factors for developing well-differentiated thyroid cancer in men. Heretofore, we did not encounter in the literature a study that was solely focused on studying risk factors for well-differentiated thyroid cancer in men. A case-control study was performed from 2005 to 2010. The case group included 204 consecutive well-differentiated thyroid cancers in male patients (180 papillary and 24 follicular including Hürthle cell). The control group comprised the same number of cases. Patients were individually matched by gender, age and place of residence. Statistical analysis included conditional univariate and multivariate logistic regression methods. According to univariate logistic regression, well-differentiated thyroid cancer in men was significantly related to smoking status, duration of smoking, number of cigarettes smoked per day, history of goiter or thyroid nodules, history of non-thyroid cancer, diabetes mellitus, radiotherapy of the head and neck, and history of malignant tumors. According to multivariate logistic regression, it was independently related to smoking status (OR = 0.36; 95% CI, 0.19-0.69), history of goiter or thyroid nodules (OR = 9.19; 95% CI, 1.25-64.58), and a history of malignant tumors (OR = 2.11; 95% CI, 1.19-7.33). Risk factors for well-differentiated thyroid cancer in men were goiter or thyroid nodules and family history of malignant tumors. Cigarette smoking was negatively associated with the disease.

Obesity, insulin resistance and vitamin D deficiency may be reversible risk factors for thyroid cancer

Obesity, insulin resistance and vitamin D deficiency may be reversible risk factors for thyroid cancer

Retrospective Analysis of Thyroid Nodules: Thyroid Cancer Risk Factors in Suzhou, China.

Thyroid nodules are common, frequently discovered in clinical practice and the incidence has increased in recent decades. They are clinically important primarily due to their malignant potential, because 2 to 5% are malignant. Correct identification of the malignancy in thyroid nodules is a diagnostic challenge, leading to potentially unnecessary surgery in patients for whom final histology is benign. Because there is no accurate preoperative detection, it is very important to predict the risk of malignancy in patients with nodular thyroid disease. The medical records of 405 patients who underwent surgery for nodular thyroid disease were retrospectively reviewed. Then clinical parameters and preoperative serum markers were compared between benign thyroid nodular disease and thyroid cancer groups. Younger than 40 years (OR 2.14, 95% CI 1.02 - 4.47, p = 0.044), preoperative TSH levels equal to or higher than 1.79 mIU/L (OR 1.76, 95% CI 1.05 - 2.95, p = 0.033), TgAb positivity (OR 2.59 95% CI 1.25 - 5.37, p = 0.01) and nodules less than or equal to 1 cm (OR 5.51, 95% CI 2.61 - 11.66, p < 0.001) were associated with increased risk of thyroid cancer in patients with thyroid nodules. The retrospective analysis suggests that younger patients with nodular thyroid disease cannot ignore the small size nodules, especially those with higher TSH levels and TgAb positivity.

Value of superb micro-vascular imaging in TI-RADS 4 thyroid nodules

Objective To evaluate the value of superb micro-vascular imaging(SMI) in the detection of TI-RADS 4 thyroid nodules. Methods A retrospective analysis of 61 patients(68 thyroid nodules) with grade 4 TI-RADS diagnosed by routine ultrasound and undergone SMI were performed, and the differences between CDFI and SMI were compared. The TI-RADS level were corrected by CDFI and SMI technology, combined with the pathological results to compare the diagnostic efficacy before and after the correction. At the same time, the related factors had been collected to evaluate the risk factors and to compare the value of SMI in benign and malignant nodules. Results SMI was more likely to detect the type Ⅲ blood flow (P=0.001) of malignant nodules. The area under the ROC curve before TI-RADS correction, after CDFI correction and SMI correction were 0.66, 0.69 and 0.78, respectively. Compared with before TI-RADS correction and after CDFI correction, the area under the curve of SMI correction was significant different (P=0.002, 0.009). There was no significant difference in the area under the curve between after CDFI correction and before correction (P=0.4196). The sensitivity of SMI was higher, but there was no significant difference (P>0.05). After single factor analysis and multivariate analysis, central blood flow and perforating blood flow found by SMI were not independent risk factors for thyroid cancer. Conclusions SMI is more effective than CDFI in detecting TI-RADS 4 thyroid nodules, and it is expected to be an auxiliary tool for the diagnosis of benign and malignant thyroid nodules. Key words: Superb micro-vascular imaging; Thyroid nodule; TI-RADS 4

Diagnostic X-Ray Exposure and Thyroid Cancer Risk: Systematic Review and Meta-Analysis.

Radiation exposure is a well-known risk factor for thyroid cancer. However, the specific effects of diagnostic radiation exposure on thyroid cancer risk are controversial. The purpose of this study was to perform a systematic review and meta-analysis to assess the effects of diagnostic radiation exposure on thyroid cancer risk. The PubMed and EMBASE databases were searched to identify eligible studies. Summary odds ratio (OR) estimates and confidence intervals (CIs) were used to compute the risk of thyroid cancer using fixed- and random-effects models. Subgroup and sensitivity analyses were performed to evaluate the potential heterogeneity. Nine studies from 12 publications were included in the meta-analysis. Overall exposure to diagnostic radiation exposure was associated with a significantly increased thyroid cancer risk (OR = 1.52 [CI 1.13-2.04]). The subgroup and sensitivity analyses revealed similar results. By type of exposure, exposure to computed tomography scans (OR = 1.46 [CI 1.27-1.68]) or dental x-rays (OR = 1.69 [CI 1.17-2.44]) were associated with an increased thyroid cancer risk. Head and neck (OR = 1.31 [CI 1.02-1.69]) and chest (OR = 1.71 [CI 1.09-2.69]) exposure to diagnostic radiation was associated with an increased thyroid cancer risk. The results of this meta-analysis indicate that diagnostic radiation exposure is associated with an increased thyroid cancer risk. Therefore, to the extent that it will not compromise the information being sought, radiation exposure to the thyroid should be minimized during diagnostic examinations.

Heart Rate Recovery and Cancer Risk: Prospective Cohort Study.

This study aims to determine the association between 2-minute heart rate recovery (HRR) and cancer risk. Each participant (5379 women; 8485 men) provided HRR obtained from treadmill tests. The outcome was site-specific cancer. Over 9 years of follow-up, 630 cancer events (258 women) were accrued. Slower HRR was associated with increased thyroid cancer risk in women ( P for trend = .0121) and colorectal cancer risk in men ( P for trend = .0034). The lowest HRR (<13 bpm) had higher hazards of thyroid cancer (hazard ratio [HR] = 2.20; 95% CI = 1.28-3.77) in women and colorectal cancer (HR = 3.08; 95% CI = 1.32-7.15) in men. In women, slower HRR and lower proportions of heart rate recovery (PHRR) were associated with higher hazards of thyroid cancer in women and metabolically related cancers (liver and colorectal) in men. Slower HRR and lower PHRR were independent risk factors for thyroid cancer in women and metabolically related cancers in men.

Thyroid cancer incidence in women and proximity to industrial air pollution sources: A spatial analysis in a middle size city in Colombia

Manizales, a mid-size city in Colombia, hosts industries like metallurgy, electrical, chemical, and rubber and plastic industrial facilities that have released into atmosphere some pollutants postulated as thyroid cancer (TC) promoters, such as dioxins and furans, dichloromethane, lead and copper. In this article we aim to detect clusters of TC and analyze their spatial association with industrial pollution. TC cases (2003–2010) were obtained from Manizales' Population-based Cancer Registry (PCR-Mz). Atmospheric emissions from industries were obtained from official reports of environmental authority. Data was spatially aggregated into census tracts and analyzed with Bayesian Besag-York and Mollié (BYM) models. Three exposure approaches were used: i) presence or absence of industries into census tracts, ii) sum of air discharges, and iii) an exposure index (EI) that considered the distance and orientation of the census tract regard to industries, average wind direction and speed, and population mobility. Models were fitted by exposure definition and sex, and included traffic and socioeconomic variables for adjustment. Using the Kulldorff's spatial exploration statistic we also performed point-data analyses in order to detect and localize clusters with individual data.Ecological regression models showed that, for women, smoothed standardized incidence ratio (sSIR) increase in 15% [95% credibility interval: 3–27%] and 63% [95%CI: 18–125%] per one standard deviation increase in EI for dichloromethane and PCDDs/Fs, respectively. Point-data analysis confirmed a cluster of female cases close to an industry emitting chlorinated solvents. These results suggest that dichloromethane and PCDDs/Fs emitted from industrial sources might be suspected as thyroid cancer risk factors.

Investigation of the Relationship Between Radiation Dose and Gene Mutations and Fusions in Post-Chernobyl Thyroid Cancer.

Exposure to ionizing radiation during childhood is a well-established risk factor for thyroid cancer. However, the genetic mechanisms of radiation-associated carcinogenesis remain not fully understood. In this study, we used targeted next-generation sequencing and RNA-Seq to study 65 papillary thyroid cancers (PTCs) from patients in the Ukrainian-American cohort with measurement-based iodine-131 (I-131) thyroid doses received as a result of the Chernobyl accident. We fitted linear regression models to evaluate differences in distribution of risk factors for PTC according to type of genetic alteration and logistic regression models to evaluate the I-131 dose response. All statistical tests were two-sided. Driver mutations were identified in 96.9% of these thyroid cancers, including point mutations in 26.2% and gene fusions in 70.8% of cases. Novel driver fusions such as POR-BRAF, as well as STRN-ALK fusions that have not been implicated in radiation-associated cancer before, were found. The mean I-131 dose in cases with point mutations was 0.2 Gy (range = 0.013-1.05 Gy), statistically significantly lower than 1.4 Gy (range = 0.009-6.15 Gy) for cases with fusions (P < .001). No driver point mutations were found in tumors from individuals who received more than 1.1 Gy of radiation. Relative to tumors with point mutations, the proportion of tumors with gene fusions increased with radiation dose, reaching 87.8% among individuals exposed to 0.3 Gy or higher. With a limited study sample size, the estimated odds ratio at 1 Gy was 20.01 (95% confidence interval = 2.57 to 653.02, P < .001). In addition, after controlling for I-131 dose, we found higher odds ratios for gene fusion-positive PTCs associated with several specific demographic and geographic features. Our data provide support for a link between I-131 thyroid dose and generation of carcinogenic gene fusions, the predominant mechanism of thyroid cancer associated with radiation exposure from the Chernobyl accident.

Insulin Resistance: Any Role in the Changing Epidemiology of Thyroid Cancer?

In the past few decades, the incidence of thyroid cancer (TC), namely of its papillary hystotype (PTC), has shown a steady increase worldwide, which has been attributed at least in part to the increasing diagnosis of early stage tumors. However, some evidence suggests that environmental and lifestyle factors can also play a role. Among the potential risk factors involved in the changing epidemiology of TC, particular attention has been drawn to insulin-resistance and related metabolic disorders, such as obesity, type 2 diabetes, and metabolic syndrome, which have been also rapidly increasing worldwide due to widespread dietary and lifestyle changes. In accordance with this possibility, various epidemiological studies have indeed gathered substantial evidence that insulin resistance-related metabolic disorders might be associated with an increased TC risk either through hyperinsulinemia or by affecting other TC risk factors including iodine deficiency, elevated thyroid stimulating hormone, estrogen-dependent signaling, chronic autoimmune thyroiditis, and others. This review summarizes the current literature evaluating the relationship between metabolic disorders characterized by insulin resistance and the risk for TC as well as the possible underlying mechanisms. The potential implications of such association in TC prevention and therapy are discussed.

Contribution of industrial density and socioeconomic status to the spatial distribution of thyroid cancer risk in Hangzhou, China

BackgroundThe thyroid cancer (TC) incidence in China has increased dramatically during the last three decades. Typical in this respect is the case of Hangzhou city (China), where 7147 new TC cases were diagnosed during the period 2008–2012. Hence, the assessment of the TC incidence risk increase due to environmental exposure is an important public health matter. MethodsCorrelation analysis, Analysis of Variance (ANOVA) and Poisson regression were first used to evaluate the statistical association between TC and key risk factors (industrial density and socioeconomic status). Then, the Bayesian maximum entropy (BME) theory and the integrative disease predictability (IDP) criterion were combined to quantitatively assess both the overall and the spatially distributed strength of the “exposure-disease” association. ResultsOverall, higher socioeconomic status was positively correlated with higher TC risk (Pearson correlation coefficient=0.687, P<0.01). Compared to people of low socioeconomic status, people of median and high socioeconomic status showed higher TC risk: the Relative Risk (RR) and associated 95% confidence interval (CI) were found to be, respectively, RR=2.29 with 95% CI=1.99 to 2.63, and RR=3.67 with 95% CI=3.22 to 4.19. The “industrial density-TC incidence” correlation, however, was non-significant. Spatially, the “socioeconomic status-TC” association measured by the corresponding IDP coefficient was significant throughout the study area: the mean IDP value was −0.12 and the spatial IDP values were consistently negative at the township level. It was found that stronger associations were distributed among residents mainly on a stripe of land from northeast to southwest (consisting mainly of sub-district areas). The “industrial density-TC” association measured by its IDP coefficient was spatially non-consistent. ConclusionsSocioeconomic status is an important indicator of TC risk factor in Hangzhou (China) whose effect varies across space. Hence, socioeconomic status shows the highest TC risk effect in sub-district areas.

Nevi, Ambient Ultraviolet Radiation, and Thyroid Cancer Risk: A French Prospective Study.

Incidence rates have increased considerably worldwide for both differentiated thyroid cancer and cutaneous melanoma, and two-way associations between these neoplasms have been described. Whether melanoma risk factors are associated with thyroid cancer risk remains unknown. Using Cox regression modeling, we prospectively analyzed the relationship between self-reported pigmentary traits, baseline residential ultraviolet (UV) exposure, and thyroid cancer risk in 86,960 women from the E3N cohort, followed-up over 1990-2008 through biennial questionnaires. We assessed associations of pigmentary traits and UV exposure with personal history of benign thyroid diseases using logistic regression modeling. All statistical tests were two sided. In models adjusted for age and thyroid cancer risk factors, number of nevi was positively associated with thyroid cancer risk ("very many" vs. "none": hazards ratio [HR] = 1.7, 95% confidence interval [CI] = 1.0, 2.8; Ptrend = 0.01), independently of residential UV exposure or iodine intake. Risk was inversely associated with latitude and positively associated with mean daily UV level at baseline (HRs for the fourth vs. first quartile of latitude and spring/summer UVB level = 0.7, 95% CI = 0.5, 0.9; Ptrend = 0.03, and HR = 1.9, 95% CI = 1.4, 2.7; Ptrend = 0.02, respectively); associations were restricted to women with dietary iodine below the median intake. Number of nevi and UV level were also associated with personal histories of dysthyroidism and of goiter/nodules, although more weakly so. Our results suggest that number of nevi and residential UV exposure are associated with the risks of thyroid cancer and benign conditions. They point to novel pathways in thyroid cancer or melanoma etiologies and warrant replication.

Attributable risk fraction of four lifestyle risk factors of thyroid cancer: a meta-analysis.

Lifestyle risk factors such as obesity, overweight, smoking and radiation exposure related to thyroid cancer. This study estimated the amount of excess risk that attributed to risk factors. Major electronic databases were searched until February 2016. Epidemiological studies addressing the association between lifestyle risk factors and thyroid cancer were enrolled. The results were expressed as ARF with 95% confidence intervals (CIs) using a random-effects-model. We identified a total of 13 321 references and included 17 studies. The excess risk of thyroid cancer attributable to radiation exposure was 14% (95% CI: 5%, 23%; eight studies, I2 = 88.7%), to obesity was 13% (95% CI: 5%, 21%; four studies, I2 = 68.7%), to overweight was 10% (95% CI: 2%, 17%; four studies, I2 = 4.1%) and to smoking was -13% (95% CI: -33%, 6%; five studies, I2 = 30.6%). So obesity, overweight and radiation exposure are significantly associated with increased thyroid cancer risk and smoking has a protective effect on thyroid cancer but not significant. A significant amount of the incidence of thyroid cancer is attributable to lifestyle risk factors. Since these factors are entirely preventable, so it is necessary to reduce factors that are associated with increased thyroid cancer risk and proper education to the community. Thus weight loss and protection against radiation can effectively reduce the incidence rate of thyroid cancer but smoking can have a protective effect.

Results of Screening in Familial Non-Medullary Thyroid Cancer.

Although a family history of thyroid cancer is one of the main risk factors for thyroid cancer, the benefit of screening individuals with a family history of thyroid cancer is not known. A prospective cohort study was performed with yearly screening using neck ultrasound and fine-needle aspiration biopsy of thyroid nodule(s) >0.5 cm in at-risk individuals whose relatives were diagnosed with familial non-medullary thyroid cancer (FNMTC). The eligibility criteria were the presence of thyroid cancer in two or more first-degree relatives and being older than seven years of age. Twenty-five kindred were enrolled in the study (12 families with two members affected, and 13 with three or more members affected at enrollment). Thyroid cancer was detected by screening in 4.6% (2/43) of at-risk individuals from families with two members affected, and in 22.7% (15/66) of at-risk members from families with three or more patients affected (p = 0.01). FNMTC detected by screening was characterized by a smaller tumor size (0.7 ± 0.5 cm vs. 1.5 ± 1.1 cm; p = 0.006), a lower rate of central neck lymph node metastases (17.6% vs. 51.1%; p = 0.02), less extensive surgery (hemithyroidectomy 23.5% vs. 0%; p = 0.002), and a lower rate of radioactive iodine therapy (23.5% vs. 79%; p < 0.001) compared to those affected at enrollment. Screening of at-risk family members resulted in earlier detection of low-risk FNMTC and was associated with a less aggressive initial treatment. Screening with thyroid ultrasound should be considered in kindred with three or more family members affected by FNMTC. Since active screening might be associated with the risk of overtreatment, it should be implemented with caution, specifically in elderly individuals.

Obesity, Insulin Resistance and Vitamin D Deficiency may be Reversible Risk Factors for Thyroid Cancer

Obesity, Insulin Resistance and Vitamin D Deficiency may be Reversible Risk Factors for Thyroid Cancer